ELECTRICAL ENGINEERING

Solar cells based on conjugated polymers are attracting increasing interest due to their potential to enable a renewable energy technology based on simple and low cost manufacture. Devices made from blends of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) have been widely studied and are consistently reported to produce efficiencies over 3%. Regioregular P3HT is known to be a good hole transporting polymer with relatively long wavelength absorption, producing films with a highly crystalline morphology and good charge mobility (10 -4 cm 2 V -1 s -1 ). According to a model presented by Scharber et al., polymer:PCBM devices could be improved to produce energy conversion efficiencies of up to 11% by replacing P3HT with an electron donating polymer that has better optimised electronic energy levels. In particular, by decreasing the LUMO level of the donor while keeping the HOMO at the same level as P3HT, the reduced band gap would allow a greater light harvesting ability without compromising the open circuit voltage (V oc ).

The effect of the addition of 1,8-octanedithiol (ODT) during processing on the microstructure of blend films of poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b 0 ]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) and [6,6]phenyl-C 71 butyric acid methyl ester ([70]PCBM) is studied. Grazing incidence X-ray diffraction and absorption spectroscopy show that the crystalline order of PCPDTBT increases when ODT is introduced in the solution phase either to neat polymer systems or to blends with [70]PCBM. The increased crystalline order is accompanied by less dispersive hole transport in the polymer, and leads to a more efficient formation of a percolating fullerene network within the blend. This contrib-utes to an increase in photocurrent generation. However, the bimolecular recombination rate as determined from photovoltage transients increases upon addition of ODT, limiting the power conversion efficiency to values well below those expected from the energy levels of PCPDTBT. We propose some explanations for this increase in bimolecular recombination, based also on variable angle spectroscopic ellipsometry measurements. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 717-724, 2011

It has been stated repeatedly that actively participating in rehabilitation programs increases the benefits and the effectiveness of the therapy. In developing robotic devices for stroke rehabilitation, the existing use of boring task interfaces produces a significant reduction in elderly patient motivation. To combine robotaided therapy with appealing games, then, is not only a matter of creating entertainment, but a real necessity for motor recovery. Besides emphasizing a lack of attention to elderly patients in conceiving games for poststroke rehabilitation, this paper suggests a tool that consolidates the gaming scenario criteria for both rehabilitation and elderly entertainment. Conclusions are then formed from the adaptability of existing games to identify the direction of future game development.

The use of autonomous hybrid power system is being popular due to the continuous increasing gap between demand and supply of conventional energy sources and intermittent nature of renewable energy sources. Normally, the renewable energy source such as wind using induction generator generate electricity but induction generators require reactive power for its operation and this demand is continuously changing by the variation of load and wind power. Though synchronous generator used in hybrid system for generating power through diesel system is supplying reactive power to the system but another source having fast response for reactive power supply is required to fulfill this demand. In this paper, the SVC and STATCOM are used and compared as a reactive power compensator.

Bearing Faults in rotating machinery occur as low energy impulses in their vibration signal and are lost in the noise. This signal has to be properly denoised before analyzing for effective condition monitoring. This paper proposes a novel method to denoise and analyze such a noisy signal. The Undecimated Discrete Wavelet Transform (UDWT) with Morlet wavelet based De-noising method is used to denoise the signal. Then this denoised signal is decomposed by Empirical Mode Decomposition (EMD) into a number of Intrinsic Mode Functions (IMF). The impulses in the signal, corresponding to the characteristic fault frequency, are seen clearly in the FFT of the IMFs. A Fast Fourier Transform (FFT), Wavelet Transform (WT), Empirical Mode Decomposition and Envelope Detection are also performed with the acquired signal and all the results are compared with the proposed method. These results clearly show the effectiveness of proposed method in detecting the faults.

Condition monitoring for rotating equipment is very cost effective in prevention of drastic failures in industries. Vibration based bearing fault detection is a widely used and implemented method for condition monitoring. When a localized fault occurs in a bearing, it causes short impulses of vibration. These impulses are mostly lost in the background noise in the plant area. To effectively bring out the impulses immersed in the noise, effective signal processing method has to be employed. Usual methods of signal analysis in time and frequency domain are not very effective. An energy based operation on the signal is required to effectively reduce the noise and bring out the fault impulses. This paper exploits the ability of Teager-Keiser Energy Operator (TKEO) in extracting transient components in the signal, thereby bringing out the characteristic fault frequency peaks. This paper also shows the usefulness of neutral network based fault classificationcoupled with TKEO to identify f...

Prion (PrP) and amyloid-β (Aβ) peptides are involved in the neuronal loss that occurs in Prion disorders (PrD) and Alzheimer's disease (AD), respectively, partially due to Ca 2+ dysregulation. Besides, the endoplasmic reticulum (ER) stress has an active role in the neurotoxic mechanisms that lead to these pathologies. Here, we analyzed whether the ER-mediated apoptotic pathway is involved in the toxic effect of synthetic PrP and Aβ peptides. In PrP106-126-and Aβ1-40-treated cortical neurons, the release of Ca 2+ through ER ryanodine (RyR) and inositol 1,4,5-trisphosphate (IP 3 R) receptors induces ER stress and leads to increased cytosolic Ca 2+ and reactive oxygen species (ROS) levels and subsequently to apoptotic death involving mitochondrial cytochrome c release and caspases activation. These results demonstrate that the early PrP-and Aβ-induced perturbation of ER Ca 2+ homeostasis is a death message that leads to neuronal loss, suggesting that the regulation of ER Ca 2+ levels may be a potential therapeutical target for PrD and AD.

Prion (PrP) and amyloid-β (Aβ) peptides are involved in the neuronal loss that occurs in Prion disorders (PrD) and Alzheimer's disease (AD), respectively, partially due to Ca 2+ dysregulation. Besides, the endoplasmic reticulum (ER) stress has an active role in the neurotoxic mechanisms that lead to these pathologies. Here, we analyzed whether the ER-mediated apoptotic pathway is involved in the toxic effect of synthetic PrP and Aβ peptides. In PrP106-126-and Aβ1-40-treated cortical neurons, the release of Ca 2+ through ER ryanodine (RyR) and inositol 1,4,5-trisphosphate (IP 3 R) receptors induces ER stress and leads to increased cytosolic Ca 2+ and reactive oxygen species (ROS) levels and subsequently to apoptotic death involving mitochondrial cytochrome c release and caspases activation. These results demonstrate that the early PrP-and Aβ-induced perturbation of ER Ca 2+ homeostasis is a death message that leads to neuronal loss, suggesting that the regulation of ER Ca 2+ levels may be a potential therapeutical target for PrD and AD.

Worldwide, most patients with asthma are treated in primary care. Optimal primary care management of asthma is therefore of considerable importance. This IPCRG Guideline paper on the management of asthma in primary care is fully consistent with GINA guidelines. It is split into two sections, the first on the management of adults and schoolchildren, and the second on the management of pre-school children. It highlights the treatment goals for asthma and gives an overview of optimal management including the topics which should be covered by the primary care health professional when educating a patient about asthma. It covers the classification of the disease, the stepwise approach to pharmacologic therapy, disease monitoring, the management of exacerbations, and the identification of patients at risk of asthma death.

Background: Clinical trials show that asthma can be controlled in the majority of patients, but poorly controlled asthma still imposes a considerable burden. The level of asthma control achieved reflects the behaviour of both healthcare professionals and patients. A key challenge for healthcare professionals is to help patients to engage in self-management behaviours with optimal adherence to appropriate treatment. These issues are particularly relevant in primary care, where most asthma is managed. An international panel of experts invited by the International Primary Care Respiratory Group considered the evidence and discussed the implications for primary care practice.

Strongly confined nano-systems, such as one-dimensional nanowires, feature deviations in their structural, electronic and optical properties from the corresponding bulk. In this work, we investigate the behavior of long-wavelength, optical phonons in vertical arrays of InAs nanowires by Raman spectroscopy. We attribute the main changes in the spectral features to thermal anharmonicity, due to temperature effects, and rule out the contribution of quantum confinement and Fano resonances. We also observe the appearance of surface optical modes, whose details allow for a quantitative, independent estimation of the nanowire diameter. The results shed light onto the mechanisms of lineshape change in low-dimensional InAs nanostructures, and are useful to help tailoring their electronic and vibrational properties for novel functionalities.

Negative Differential Transconductance in a MoS2/WSe2 Heterojunction Field Effect Transistor AHMAD ZUBAIR, Massachussetts Institute of Technology, AMIRHASAN NOURBAKHSH, Massachussetts Institute of Technology, IMEC, MILDRED DRESSELHAUS, Massachussetts Institute of Technology, STEFAN DE GENDT, IMEC, TOMAS PALACIOS, Massachussetts Institute of Technology -In this work, we demonstrate the negative transconductance in heterojunction transistors made of two-dimensional materials for the first time. Negative transconductance plays a key role in multi-valued logic/memory and frequency multiplication circuits. The simpler fabrication method of stacked van der Waals heterostructures compared to the conventional bulk semiconductors and large area CVD growth of the layered 2D materials systems makes it a prime candidate for scalable novel applications of their heterostructures. Vertically stacked MoS 2 /WSe 2 heterostructures are fabricated by mechanical exfoliation and an in-house dry transfer process. A two-step process of e-beam lithography and metal deposition (Au on MoS 2 , and Pd on WSe 2 ) were performed to fabricate n-type MoS 2 and ambipolar WSe 2 FET. The transfer characteristics on the non-overlapping regions shows the expected characteristics of the n-type, MoS 2 FET and ambipolar WSe2 FET. At the same time, the transfer characteristics of the overlapping region between MoS 2 and WSe 2 show negative differential transconductance. With proper scaling and careful optimization this negative differential transconductance will lead to novel applications.